How to ask for permission in facebook application?

I am developing a facebook application (FBML) and i want to ask for certain extended permissi开发者_如何转开发ons for the first time a user comes to app. How to do that?

Note that I am not using new graph API for this app.

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There are two ways I can think of:

1. You use the fb:prompt-permission tag to render a link which when clicked pops up the extended permissions dialog.

2. You redirect non-auth'd users to the app login page, requesting the appropriate permissions:

<fb:if-is-app-user>
<!-- your normal code -->
<fb:else>
  <fb:redirect url="http://www.facebook.com/login.php?v=1.0&api_key=[your_app_key]&next=[your_canvas_page_URL]&canvas=&req_perms=[comma-delimited list of permissions]"/>
</fb:else>
</fb:if-is-app-user>

Example redirect URL: http://www.facebook.com/login.php?v=1.0&api_key=147433427237&next=http%3A%2F%2Fapps.facebook.com%2Fkickabout%2F&canvas=&req_perms=publish_stream

See: https://developers.facebook.com/docs/authentication/